Ah, so now we use solar cells to produce electricity, with which we split water atoms into oxygen and hydrogen. And then later, we burn the hydrogen to AGAIN produce electricity, which we use for all kinds of other stuff...
I\'m wondering: every conversion costs an amount of energy, causing the efficiency to drop. So why transform electricity into hydrogen, and then back again? Wouldn\'t it be smarter to just skip the last two conversions, and just store the electricity directly? What do we stand to gain from these extra conversions?

Boiling Oil, what we gain is storage capability, portability, and slow accumulation/fast release capability. I don\'t think we need to compete on overall efficiency since there is generally less impact from the inefficiencies related to hydrogen than fossil fuels.
There are concerns about catalysts and storage chemistry/release rates that do merit concern, but they must be compared to the existing fuels and their dependence on a much larger infrastructure that limits our ability to operate independently, especially during natural disasters, etc. Rational safety factors may decrease overly shortsighted, purely economic, efficiency, but that has been true with every previous energy source I can think of.

Batteries tend to be expensive to produce, dirty, and lose their efficiency over time. Efficient hydrogen production has been sought after to take the place of batteries as a storage solution. Your name says is all boiling (heating) oil or heating salt are two other methods used to store energy produced by solar at times when the sun isn\'t out. The problem with hydrogen production has been older catalysts are expensive made from platinum. This is a cheaper way to get the job done.

You don\'t burn the hydrogen Dummy!! Use it in a fuel cell... For a super clean energy source when the sun isn\'t shining.

BoilingOil: Could you give an example of a way to \'store the electricity directly\'? Maybe I\'m dumb, but it\'s not a phrase that is making any sense to me.

Surely the best way is to feed surplus energy back into the grid, which is credited to your account. You don\'t need to store it. That\'s what we do in the UK.

fatfox-I think he means batteries. That point is addressed by jimyoung and Dimitri Leontari

It would be good if multiple conversions were not required to have readily available energy. Boilingoil, you are correct in assuming that most mechanical, electrical and biological systems conform to the second law of thermodynamics in that they always tend to increase entropy (or decrease the efficiency of conversion), this tends to be especially so if multiple conversions are involved. However energy conversion problems or efficiencies are generally confined to specific input to “desired” output conversions. The trick to sustainability is to reuse every output from the conversion process to increase overall “efficiency”. For example: a CHP (Combined Heat Power Generator) that converts methane (NG) into electricity at up to 47% eff. and that reclaims the heat from the exhaust/cooling system to warm buildings, the total efficiency can be up to 90%. Now if you use a biogas system to create the methane through anaerobic digestion you can use nearly any waste organic matter (including that from landfill etc) to produce a gaseous fuel that can be stored and compressed for use in vehicles or generation, using existing Natural Gas equipment. Anaerobic digestion is a naturally occurring phenomenon that consumes organic material (or Carbohydrates) and converts them to methane (Hydrocarbons), with the only process waste being pathogen free soil improving mulch. The beauty of this process is that it rides piggy back on human consumption ie more food consumption = more organic waste. Also it uses organic (plant or animal waste) waste that is no longer fit for human consumption, unlike biodiesel, ethanol etc. But I suppose the best thing is that organic material is solar powered through photosynthesis, and plants and animals store this energy chemically, in the form of carbohydrates and fats until it can be released in the biogas system. Might seem like a lot of conversions to achieve the desired output, but along the way it produces numerous benefits to the environment and humanity. It is my opinion that hydrogen and any of its derivatives are products of fossil fuel focused development, for the exploitation of many for the benefit of a few...in this case they are obviously 'playing' with the figures to keep their 'efficiencies' high ;)
@ fatfox Capacitors will do this with a relatively low energy density, a battery obviously stores the energy chemically though

Boiling Oil. Electricity is an \"instant\" thing like light. You can\'t store light by shining it into a box all day then closing the lid. A capacitor stores electrons directly but storing a significant amount is impractical. So electricity needs to be converted into something else to store it. Like chemical energy or heat.... or hydrogen.

fatfox:
duh! Just shovel it into a skip! XD